i got and 300 inlinne six 4 speed with and 9 inch 2.47 rearend and i just got back from the junk yard and i pulled and 9 inch 3.00 rearend ...........
what are the differnce iam going to be able to tell? thanx for all the help

 

forgot to ask...... how is this going to affect my low end and top end
am i going to be able to get of the line better?

 

Going from 2.47 to 3.00 you will feel more acceleration power. The lower (numerically higher) ratio puts the engine into it's powerband quicker and at lower vehicle speeds, making the truck peppier around town, when loaded, and when pulling hills. The engine rpm's will be a little higher at all vehicle speeds so the top speed will be slightly lower. Neither of those are considered to be low ratios, unless you're running really small diameter tires, so I wouldn't worry about the top speed.